Study On The Mechanism Of Zinc-philic Additives Regulating The Stability Of Zinc Anode/electrolyte Interfac

Aqueous Zn-ion batteries（AZIBs）provide a solution for high operating cost and safety issue of lithium-ion batteries owing to their utilization of cheap Zn metal and non-flammable aqueous electrolyte for energy storage,making them the most promising energy storage devices.Unfortunately,commercial application of AZIBs is severely hindered by dendritic growth,hydrogen evolution and electrode corrosion of Zn anode.These issues can be solved by tuning the interfacial property between Zn anode and electrolyte using different additives.Herein,three types of zinc-affinitive additives were designed for improved stability of Zn anode.The main investigations are as follows:（1）Inspired by brighteners in electroplating industry,dibenzenesulfonimide（BBI）was introduced into Zn SO₄ electrolyte.BBI effectively adjusts the double electric layer of Zn anode and isolates the water molecule from its surface,thereby preventing hydrogen evolution reaction and electrode erosion.Furthermore,BBI can regulate Zn²⁺deposition along the electrode surface to prevent dendrite formation.The stability of Zn anode was obviously improved by adding BBI.As a result,Zn||Zn symmetric battery with BBI additive delivered an ultra-long cycle life of over 500 h at high current density and high area capacity(10 m A cm^-2,10 m A h cm^-2).（2）The solid electrolyte interphase（SEI）was in situ constructed on the surface of Zn anode by electrochemical conversion of sulfonamide additives,which improved the stability of Zn anode.XPS results showed that Zn S was the main component of SEI layer which is converted from the decomposition of benzene sulfonamide（BSA）and sulfonamide（SAs）additives.The stable SEI protect the Zn anode from the corrosion of solvent water,reducing the dendrites and parasitic reactions.Moreover,the introduction of-NH₂ can improve the affinity of SAs with Zn anode,further improving the stability of SEI layer.Thus,Zn anodes achieve improved electrochemical stability.（3）High-polarity molecules usually can regulate the solvation structure of metal ions owing to strong affinity.Thus,a general strategy was proposed to improve the electrochemical stability of Zn anode using aprotic polar solvents as electrolyte additives.The experimental results showed that aprotic polar solvents can change the solvation structure of Zn²⁺and destroy the hydrogen bond of H₂O.The decrease of solvated H₂O and free H₂O helps to alleviate the water-induced parasitic reaction,achieving uniform deposition of Zn²⁺.As a result,Zn||Zn symmetric cell reaches a long cycle life to 1200 h,which is 30 times the cycling stability in Zn SO₄ electrolyte.More importantly,the mechanism applies equally to other aprotic polar solvents（N,N-Dimethylformamide and N-Methylpyrrolidone）.